Fixed in changeset:   7374:72de757edf78

Also the reason for the token.py to rtoken.py change is:

  This bites me every now and again when running pytest and pdb. Some
  submodules want to load the stdlib python and end up getting roundup's
  python and thing break with N_TOKENS not defined etc.

So not directly related to the reason for this ticket,
but it does change the initial problem symptoms.